Piston



L DlcKsQN PISTON Filed Feb. 4, 1941 5 Sheets-Sheet l l'mnentor Dec. 15,i942. 1. DlcKsoN '2,394,891

PISTON Filed Feb. 4, 1941 3-Sheets-Sheet; 2

attorneys etented ee. l5, i942 g? f John Dickson, nemesis, met., @im t@seseral Motors Corporation, Detroit, Michl, s, corporation of DelawareApplication lFebMf d, 194i, Serial No. 377,360 6 Claims. (Ci. 23-176)This invention relates to pistons, and especially construction of a,piston for e two cycle engine, to strong but light pistons for two cycleinternal according to the invention. combustion engines. Fig. 2 is a.sectional View on line 2-2 of Fig. 1.

In modern high speed two cycle engines, the Fig. 3 is a, view on linei-- oi' Fig. 1, conditions under which the pistons have to oper- Fig. 4is e view on line @-8 of Fig. l with Pori ate are particularly severe.As compared with a broken BWBY- 10111' cycle engineI there are twice thenumber of Fig. 5is a, View Online 5--5 Of* Fig. 3. power strokes in e.given time, at a given speed, Fig. 6 is a sectional view of a modifiedform oi and hence, other things being equal, there is Construction f oPiSon coordlng to the inl/ell* considerably more heat to be dissipatedthrough l0 tion. the parts. Fig. 'l is e sectional View on line T-l ofFig. 6. Since there is no suction stroke in a. two cycle Fig. 8 iS oSectional View 0f another modied engine, the gas pressure loads on thepiston (of form of construction of a piston according to s single actingengine) are always in the same the invention. direction, and only athigher speeds are-they l Fig. 9 is a sectional view of a. modified formof exceeded by inertia forces in an opposite direcconstruction of apiston according to the invention. For this reason the bearing betweenthe 191011, for 11S@ Wi o Connecting rod having a conpiston and itsconnecting rod is mainly subjected Venfionol PSOD pill booileto e. loadin one direction, and that a compreion FigiS o Sectional VIEW 0l Portsof he Piston load on the connecting rod. If therefore an ade` inSeparated rolaonShiD With Ports broken B'Woy. quete bearing to transmitthe load in this direc- F18- l 1S 2S Sectional View on line H- l voftion is provided, it is only necessary to provide Fisl0- keeper pieceswith a. much smaller bearing arse. Fig. l2 is a. plan view of the pistonas seen to take any inertia loads in en opposite direction from theunderside. end to secure the piston to the connecting rod. ll Figs. 1 to5, the piston includes 2 Crown l,

The general object of the invention is en imo Skirt 2, ond E' Strut 3,formed aS a Single molproved piston capable of withstanding high mgleeble casting. Fsstened by bolts t to the strut end onerous temperatureconditions. 3. 1S o bowing piece for o Connecting rod l.

A more specific object of the invention is e The Strut 3 iS Cylindrical,and fOImS all inner symmetricalpiston structure especially suited for mCircular Wan spaced from the Skirt and if i8 e two ycycle engine, inwhich the bearing for the connected to the crown with archedstrengtheneonnectmg rod is subtended directly from the ing obs Such es iIt iS Slotted with elongated crown of the piston by a Strut;i forming annner holes such as iii parallel to its axis, and thereby circular w81]spaced from the skirt of the pistou constitutes a. plurality of loadsupporting col- Another object of the invention is a. piston in 11111115Capable of bonding to permit expansion of wbibh the Strut is notsubjected o direct bending the crown relatively to the strut withoutunduly stresses from the direct load on the piston, in high bemlg Stre@in the lottery Mld it has which expansion of the piston crown cm, takee. ineen diameter twothirds that of the piston piece without unduly highbending stresses m diameter so that it is st the center of pressure ofthe strut, and longitudinal @merende expansion if the load 0n thePiston' t0 minimize bending between the strut and the'skirc 1s freelypex- Sms-58S in the Crown,- mg'tte Because the strut 1s cylindricel andnot con- Another object of the invention is to achieve ical, the directload on the piston causes no direct bending stresses on the strut f einthe Greg g Objects with a piston structure m The bering piece d has a.convex semi-cylinwhich side loeds due to Obliquity of the connect newbearing surm m with a bronze lining mg rod are directly transmitted tothe piston E3 to woperete with e. concave ercuete bearing am@ h surfacetl on the connecting rod l, and has s, ir-

' A 5ml further Object 0f the invention is a' D15 cular flange portionig with e cylindrical surton structure in which the conventional pistong) face which is a Sliding gt in @he Skirt, and pin andriswn ein bossesare eliminate@ through which sie@ loses due to ebiiquity of the Theabove and other objects of the invention Connecting md @an bg mansmtlddirectly bbc will be apparent as the description proceeds. tween theskirt end the bearing piece, while lon In the drawings: gitudinaldifferential expansion between the strut and the skirt is freelypermitted. There ere four Fig. 1 is e. sectional view of a preferredform of radial strengthening ribs such as Il for the bearu ing piece 6.

At the same time, the ilange portion I5 forms a. closure for a coolingchamber including the annular space between the skirt and the strut, andthe space to the interior of the latter; there being holes |1'providedwith tubular extensions i8, through the circular flange portion 15,through which lubricating oil may be projected to cool the piston, andto lubricate the connecting rod bearing through a hole i9extendingthrough the bearing piece 6 and its bronze lining |3. Thetubular extensions |8 maintain a reservoir of lubricating oil in thecooling'chamber.

The bolts 4 which hold the bearing piece 6 to the strut 3, extend alsothrough keeper pieces 20 and 2|which take any inertia loads in anopposite direction to the gas pressure loads and secure' the piston andconnecting rod together.

This is desirable in the event of partial seizure Y of the piston skirtand cylinder liner and also to enable the piston to be withdrawn withthe rod. Y

In the modification shown in Figs. 6 and '1, the piston crown 3| and theskirt 32 are formed separately, and welded together at 33, the strutpart 34 and the bearing part 35 for the connecting.

rod 31, being formed in one piece having a male threaded connection at30, with a female thread'- ed part 39 of the crown 3|. v

The strut part 34 is cylindrical and is integral with thel bearing part35, which has a concave semi-cylindrical bearing surface 4| with abronze lining 43,V to cooperate with a convex arcuate bearing surface 44on the connecting rod 31.

The crown 3| is strengthened by six radial ribs such as 48, while thereare fourY radial strengthening ribs such as 41 for the strut 34.

'I'here are twelve holes such as ,4I through the part 39 of the crown3|, and four slotted holes such as 48 through the strut 34.V

The bearingpart 35 has a circular flange portion 50 -with a cylindricalsurface which is a sliding t in the skirt, and throughwhich side a loadsdueto Obliquity oi' the connecting rod can be transmitted directlybetween the skirt and.

the bearing part 35, while longitudinalV dinerential expansionY betweenthe parts 34 and 3l and the skirt 32 is freely permitted.

At the same time, the flange portion 50 forms Y a closure for a coolingchamber including the annular space between the skirt and the strut, andthe space to the interior of the latter; there being a hole`52 through athickened portion of the circular ilange portion 50, "through whichYlubricating oil may be projected tocool the piston, and to lubricatetheconnecting rod bearing through holes such as 34 extending through dowelpins such as 55, by which the bronze lining 43 is prevented from turningrelatively to the surface 4| of the part 35.

It will be appreciated that s reservoir of lubricating oil, level withthe tcp of thehole 32, is maintained in the cooling chamber.

A pair of keeper pieces such as 80, secured to the part 35 by bolts 5|,perform the function of the keeper 'pieces 20am! 2| oi Figs. 1 to 5.

In the modification shown in Fig. 8, the piston crown 1| and the skirt12 are formed separately, and welded together at ,13, the strut part 14and the bearing part 1E ior the connecting rod 11, being formed in onepiece having a emale threaded connection at 1B, with e. :male threadedpart 19 of thecrown 1|.

The strut part 'M is cylindrical and is integral liu with the bearingpart 15, which has a convex` semi-cylindrical bearing surface 8| with abronze lining 03, to cooperate with a concave Aarcuate bearing surface04 on the connecting rod 11.Y

The crown 1| is strengthened by six radial ribs such as 83, while thereare four radial strengthening ribs such as 81 for the strut 14.

There are twelve holes such as 03 through the part 18 of the crown 1|,and four slotted holes such as 89 through the strut 14.

At the juncture of the parts 14 and 1I, there is a circular flange witha cylindrical-surface which is a sliding t in the skirt, and throughwhich side loads due to Obliquity o! the connecting rod can betransmitted directly between the skirt and the bearing part 15, whilelongitudinal diilerential expansion between the parts 14 and 16 and theskirt 12 is freely permitted.

At the same time, the flange portion l0 forms a closure for a coolingchamber including theV annular space between the skirt and the strut,

of the ilange S0, through which lubricating oil Y may be projected tocool the piston, and to lubricate the connecting rod bearing through ahole 34 extending through the bearing part 13 and its bronze lining 83.

oi' the holes 9| -and 32 is maintained in the cool` ing chamber. i

A pair of keeper pieces such as 30, secured to the part 15 by bolts 91,take any inertia loads linV an opposite direction to the gas pressureloads and secure the piston, and connecting'rod to; gether.

In the modification shown in Figs. 9 to 12, the piston includes a crown|0|, a skirt |02, anda strut |03,formed as a single casting. Fastened Yby four bolts such as |04 to the strut |03, is a bearing piece IllB, fora piston pin |01.'

The strut |03 is cylindrical, forms an inner circular wall spaced fromthe skirtLand is conn cted to the crown by arched strengthening bs suchas |09. Itis slotted with elongated cles such as ||0 parallel toitsaxis, and thereby constitutes a plurality of load supporting .columnscapable of bending to permit expansion oi the crown relatively to thestrut without unduly high bending stresses in the latter, and it has amean diameter two-thirds that oi vthe piston diameter so that it is atthe center of pressure of the load on the piston, tol minimize bendingstresses in the crown.

The bearing piece |98 is bored i'or two coaxial bronze bushings and H2,in which oppositeY ends o1' the tubular pistonpin |01 are supported. Theeye ol' the connecting rod ||4 is bored for a sleeve H, within which isabronze bustling H8. f

, contour of the cylindrical surface of the bearing piece |06, which hassliding contact with the bore i of the piston skirt, is made up of twoopposite' surfaces` on flange portions i20 and |2| in a plane normal tothe axis of the piston and containing the axis or the piston pin 501,and two opposite semi-circular surfaces on ange portions |28 and Thecorresponding sur- |2|',"|24'. and |25' respectively.

There are four holes such as l" through the bearing piece III for thebolts such as |04 which' are screwed into four corresponding tappedholes |3| in suitable lug portions |32 and lll of the strut |03, tosecure the bearing piece to the strut. Side loads due to obliquity ofthe connecting rod are transmitted vdirectly between the skirt and thebearing piece through the sliding cylindrical surfaces of -theangeportions |20', |2I, |24. |25', and itl, III, |24, lil, whilelongitudinal differential expansion between the strut with the bearingpiece. and the skirt, is freely permitted.

At the same time, the flange on the'bca'rina piece forms a closure for acooling'chamber including the annular space between and the strut, andthe space to the interior of the latter: there being two holes IIIthrough the bearing piece, with extensionsy |38 through the lugs |38 ofthe strut. through which lubricating oil may be projected to cool thepiston. It will be noted that the bore of the tubular piston pin |01isopenatitsendstotheannularspace extending between the skirt and thestrut, andthat without overstressing the load carrying strut and theringbelt and piston skirt which are free from gas'pressure loading areuniform in thickness and present unbroken surfaces to the wall.

I claim:

1. A piston including acrown. a skirt, ond albearingpiecewithabearingforaconnectingrod subtended from the crown by astrut forming an inner circular wall spaced from the skirt andunconnected thereto,` said bearing piece having a -cylindrical surfacewhich a sliding fit in the skirt, whereby ingituaipn dmerenum expansionbetween the strut axfd 'the skirt is freely 315er- 1 mitten, wmie 51dethrust forces 'due to Obliquity Hof the connecting rod are directlytransmitted said sliding cylin-` to the piston skirt through dricalsurface. y, .v

2. The combination according to claim l, in

which there are holes through theinriery circular wall formed by` theystrut, and the cylindrical surface of the bearing piece lforms aclosurefor a cooling chamber including ,'the annularspace between the skirtandthe strut'andqthespace to the interior of the latter; there being ayhole through the bearing piece through which lubricating oil may beprojected, to 'cool the piston.

3. The combination according toclaim .1, in which there are holesthrough the inner circular wall formed by the strut,and the cylindricalsur-A face 'of the bearing piece forms a closure for a cooling chamberincluding the annular space between the skirt and the strut and thespace to the interior of the latter; there being a hole through thebearing piece through which lubricating loil may be projected, to coolthe piston, and to lubricate the surface of the bearing through a holein the bearing piece from the cooling chamber to the surface of thebearing.

4. The combination according to claim 1. in which the strut-iscylindrical. yhas a/mean diameter two-thirds that of the pistondiameter, and is slotted parallel with its axis.

5. A piston including a crown, a skirt, and a bearing piece with abearing for a connecting rod, subtended from the crown by a slottedcylindrical strut concentric with but spaced from and unconnected to thepiston skirt; said slotted cylindrical strut constituting a plurality ofload 'l supporting columns disposed in a circle. and

the piston diameter.l

